Spirit level

ABSTRACT

A spirit level comprising a body having a level face for setting a surface, at least one bubble vial mounted in the body, the bubble vial having a longitudinal axis generally perpendicular to the level face, and an optical transfer element fixed to the body which transfers an image of the bubble vial to a viewing plane generally parallel to the level face.

This is a continuation of PCT/IL97/00359, filed Nov. 7, 1997, and claimsthe benefit of provisional application No. 60/032,702, filed Dec. 12,1996.

FIELD OF THE INVENTION

The present invention relates to spirit levels.

BACKGROUND OF THE INVENTION

Spirit levels, also called bubble levels, are well known instrumentsused for setting horizontal or vertical surfaces. The level includes asealed vial containing an air bubble floating in a liquid. Theparticular surface is considered horizontal or vertical when the airbubble rests between predetermined graduated marks in the vial.

When setting, also called plumbing, a vertical surface with a typicalspirit level, the bubble vial is generally perpendicular to the surfacebeing set, with the result that the air bubble must be viewed from aposition which does not directly face the surface being set.Unfortunately, it is sometimes awkward or strenuous to view the airbubble from such a position. Adverse lighting conditions can alsoexacerbate difficulty in reading the bubble from such a position.

U.S. Pat. No. 4,103,430 to Schrader describes a viewing device for aspirit level including a luminescent panel and a pivotable mirrorarranged to provide an illuminated image. of the air bubble which may beviewed without having to look directly at the air bubble vial. However,the air bubble must still be viewed from a position which does notdirectly face the surface being set.

SUMMARY OF THE INVENTION

The present invention seeks to provide a novel spirit level wherein theair bubble may be viewed from a position which directly faces a surfacebeing set.

There is thus provided in accordance with a preferred embodiment of thepresent invention a spirit level including a body having a level facefor setting a surface, at least one bubble vial mounted in the body, thebubble vial having a longitudinal axis generally perpendicular to thelevel face, and an optical transfer element fixed to the body whichtransfers an image of the bubble vial to a viewing plane generallyparallel to the level face.

In accordance with a preferred embodiment of the present invention theoptical transfer element enlarges the image. In accordance with anotherpreferred embodiment of the present invention, the optical transferelement diminishes a size of the image. Illumination apparatus may beprovided for illuminating the image.

In accordance with a preferred embodiment of the present invention theoptical transfer element includes a reflective surface arranged at anangle to the bubble vial and to the viewing plane and which reflects theimage of the bubble vial to the viewing plane. The reflective surfacemay be a mirror or a prism, for example. In accordance with anotherpreferred embodiment of the present invention the optical transferelement includes an electric viewing device.

The optical transfer element may be internally or externally mounted inor on the spirit level. Additionally, the optical transfer element maybe detachable from the spirit level.

In accordance with a preferred embodiment of the present invention theoptical transfer element is an add-on accessory which may be attached tothe spirit level.

There is also provided in accordance with a preferred embodiment of thepresent invention a method for facilitating viewing a bubble vial of aspirit level while setting a vertical surface, the bubble vial having alongitudinal axis generally perpendicular to the vertical surface, themethod including the steps of fixing an optical transfer element to thespirit level which transfers an image of the bubble vial to a viewingplane generally parallel to the vertical surface, and viewing the bubblein the viewing plane.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description, taken in conjunction with thedrawings in which:

FIG. 1 is a simplified pictorial illustration of a spirit level,constructed and operative in accordance with a preferred embodiment ofthe present invention;

FIG. 2 is a simplified pictorial illustration of the spirit level ofFIG. 1 tilted away from a vertical surface being set;

FIG. 3 is a simplified pictorial illustration of a spirit level,constructed and operative in accordance with another preferredembodiment of the present invention;

FIG. 4 is a simplified pictorial illustration of the spirit level ofFIG. 3 tilted relative to a vertical surface being set;

FIG. 5 is a simplified pictorial illustration of a spirit level,constructed and operative in accordance with another preferredembodiment of the present invention, and including an optical transferelement which enlarges an image of a bubble vial;

FIG. 6 is a simplified pictorial illustration of a spirit level,constructed and operative in accordance with yet another preferredembodiment of the present invention, and including an optical transferelement which diminishes a size of an image of a bubble vial;

FIG. 7 is a simplified pictorial illustration of a spirit level,constructed and operative in accordance with a further preferredembodiment of the present invention, and including an optical transferelement which transfers an image of a bubble vial electrically; and

FIG. 8 is a simplified pictorial illustration of a spirit level,constructed and operative in accordance with yet a further preferredembodiment of the present invention, and including an optical transferelement which is an add-on accessory.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Reference is now made to FIG. 1 which illustrates a spirit level 10,constructed and operative in accordance with a preferred embodiment ofthe present invention. Spirit level 10 preferably includes a body 12having a level face 14 for setting a surface 16. Body 12 is preferablymade of a mechanically stable and durable metal alloy, as is well knownin the art. Level face 14 typically has highly accurate flatness andsmoothness. End caps 18, typically made of plastic, may be fixed to endsof body 12, as is known in the art.

Spirit level 10 preferably includes one or more bubble vials 20 mountedin body 12 for setting a vertical surface and one or more bubble vials22 for setting a horizontal surface. Bubble vial 20 preferably has alongitudinal axis 24 generally perpendicular to level face 14.

In accordance with a preferred embodiment of the present invention, anoptical transfer element 30 is fixed to body 12 which transfers an imageof bubble vial 20 to a viewing plane 32 generally parallel to thesurface 16 being set. Viewing plane 32 is preferably located on a face34 of body 12 generally parallel to level face 14. As seen in FIG. 1,optical transfer element 30 preferably includes a reflective surface 36mounted inside a hollow portion of body 12 at an angle to bubble vial 20and to viewing plane 32 which reflects the image of bubble vial 20 toviewing plane 32. Reflective surface 36 may be a polished mirror or aprism, for example. Preferably a window 38 is cut out on face 34 so thata user 40 can conveniently view the image of bubble vial 20 on viewingplane 32.

Reference is now made to FIG. 2 which illustrates spirit level 10 tiltedat an angle (t relative to vertical surface 16 being set. In theorientation of FIG. 2, it is seen that moving the bottom edge of spiritlevel 10 away from surface 16 causes a bubble 42 to move towards user 40and the image of bubble 42 is seen to move upwards at viewing plane 32.This is because optical transfer element 30 is located above bubble vial20 in the orientation of FIG. 2. It is appreciated that converselymoving the top edge of spirit level 10 away from surface 16 causesbubble 42 to move away from user 40 and the image of bubble 42 is seento move downwards at viewing plane 32.

Optical transfer element 30 may be provide with optical power. Forexample, optical transfer element 30 may be curved so as to enlarge ordistort an image of bubble vial 20.

Reference is now made to FIG. 3 which illustrates a spirit level 50,constructed and operative in accordance with another preferredembodiment of the present invention. Spirit level 50 is substantiallyidentical with spirit level 10, with like elements being referenced bylike numerals. Spirit level 50 differs from spirit level 10 in that anoptical transfer element 52 is mounted below bubble vial 20, theimportance of which is described with reference to FIG. 4.

Reference is now made to FIG. 4 which illustrates spirit level 50 tiltedat an angle β relative to vertical surface 16 being set. In theorientation of FIG. 4, it is seen that tilting the bottom edge of spiritlevel 50 away from surface 16 causes bubble 42 to move towards user 40and the image of bubble 42 is seen to move downwards at viewing plane32. This is because optical transfer element 52 is located below bubblevial 20 in the orientation of FIG. 4. It is appreciated that converselytilting the top edge of spirit level 50 away from surface 16 causesbubble 42 to move away from user 40 and the image of bubble 42 is seento move upwards at viewing plane 32.

Reference is now made to FIG. 5 which illustrates a portion of a spiritlevel 60, constructed and operative in accordance with yet anotherpreferred embodiment of the present invention. Spirit level 60 issubstantially identical with spirit level 10, with like elements beingreferenced by like numerals. Spirit level 60 differs from spirit level10 in that an optical transfer element 62 is provided that enlarges theimage of bubble vial 20. This may be accomplished, for example, bydisposing a magnifying lens 64 intermediate reflective surface 36 andviewing plane 32. Illumination apparatus 66, such as an electric lightor LED, may be provided for illuminating the image of bubble vial 20.

Reference is now made to FIG. 6 which illustrates a portion of a spiritlevel 70, constructed and operative in accordance with still anotherpreferred embodiment of the present invention. Spirit level 70 issubstantially identical with spirit level 10, with like elements beingreferenced by like numerals. Spirit level 70 differs from spirit level10 in that an optical transfer element 72 is provided that diminishes asize of the image of bubble vial 20. This may be accomplished, forexample, by disposing a diminishing lens 74 intermediate reflectivesurface 36 and viewing plane 32.

Reference is now made to FIG. 7 which illustrates a portion of a spiritlevel 80, constructed and operative in accordance with a furtherpreferred embodiment of the present invention. Spirit level 80 issubstantially identical with spirit level 10, with like elements beingreferenced by like numerals. Spirit level 80 differs from spirit level10 in that an optical transfer element 82 transfers an image of bubblevial 20 to a screen 84, such as an LCD screen, located on viewing plane32, by means of an electric viewing device 86, such as a miniaturecamera. Optical transfer element 82 does not require any reflectivesurface.

Reference is now made to FIG. 8 which illustrates a portion of a spiritlevel 90, constructed and operative in accordance with yet a furtherpreferred embodiment of the present invention. Spirit level 90 issubstantially identical with spirit level 10, with like elements beingreferenced by like numerals. Spirit level 90 differs from spirit level10 in that an optical transfer element 92 is provided which isexternally mounted on spirit level 90. Optical transfer element 92preferably includes a reflective surface 94, such as a mirror or prism,which reflects an image of bubble vial 20 to a viewing plane 96generally parallel to the surface 16 being set. Reflective surface 94 ispreferably detachable from spirit level 90 and may be hinged thereto bymeans of a hinge 98. Thus, optical transfer element 92 may be an add-onaccessory to spirit level 90.

Optical transfer element 92 may be provide with optical power. Forexample, optical transfer element 92 may be curved so as to enlarge ordistort an image of bubble vial 20. Optical transfer element 92 may alsobe rotatable about an axis 99 of bubble vial 20.

It will be appreciated by persons skilled in the art that the presentinvention is not limited by what has been particularly shown anddescribed hereinabove. Rather the scope of the present inventionincludes both combinations and subcombinations of the features describedhereinabove as well as modifications and variations thereof which wouldoccur to a person of skill in the art upon reading the foregoingdescription and which are not in the prior art.

What is claimed is:
 1. A spirit level comprising: a body having a levelface for setting a surface; at least one tubular bubble vial mounted insaid body, said bubble vial having a longitudinal axis perpendicular tosaid level face, said level face arranged to be intermediate an end ofsaid bubble vial and said surface to be set; and a mirror fixed to andentirely enclosed within said body which transfers an image of saidbubble vial to a viewing plane parallel to said level face, said imageincluding a bubble floating in said bubble vial and two graduation marksmarked on opposite sides of a longitudinal midpoint of said bubble vial,said viewing plane being located on a viewing face of said body parallelto said level face, the ends of said bubble vial not extending beyondsaid level face and said viewing face, a transparent window elementbeing located on said viewing face so that the image of said bubble vialcan be viewed through said window element in a first range of viewingangles wherein a viewer can see said image transferred via said mirror,and in a second range of viewing angles wherein the viewer can see saidimage directly through said window element without said image beingtransferred via said mirror, wherein there is an unobstructed line ofsight along a plane of said mirror.
 2. A spirit level according to claim1 wherein the plane of said mirror intersects said window element.
 3. Aspirit level according to claim 2 wherein said mirror is detachable fromsaid spirit level.
 4. A spirit level according to claim 1 wherein saidmirror intersects said window element.
 5. A spirit level according toclaim 1 wherein the plane of said mirror intersects said level faceabove a vial plane, defined as a plane which is tangent to an uppersurface of said bubble vial and perpendicular to said viewing face andto said level face.
 6. A spirit level comprising: a body having a levelface for setting a surface: at least one tubular bubble vial mounted insaid body, said bubble vial having a longitudinal axis perpendicular tosaid level face, said level face arranged to be intermediate an end ofsaid bubble vial and said surface to be set; and a mirror fixed to andentirely enclosed within said body which transfers an image of saidbubble vial to a viewing plane parallel to said level face, said imageincluding a bubble floating in said bubble vial and two graduation marksmarked on opposite sides of a longitudinal midpoint of said bubble vial,said viewing plane being located on a viewing face of said body parallelto said level face, the ends of said bubble vial not extending beyondsaid level face and said viewing face, a transparent window elementbeing located on said viewing face so that the image of said bubble vialcan be viewed through said window element, wherein said mirror defines aplane along the surface thereof, said plane containing a line of sightwhich is not obstructed by said viewing face.
 7. A spirit levelcomprising: a body having a level face for setting a surface; at leastone tubular bubble vial mounted in said body, said bubble vial having alongitudinal axis perpendicular to said level face, said level facearranged to be intermediate an end of said bubble vial and said surfaceto be set; a mirror fixed to and entirely enclosed within said bodywhich transfers an image of said bubble vial along a first line of sightto a viewing plane parallel to said level face, said image including abubble floating in said bubble vial and two graduation marks marked onopposite sides of a longitudinal midpoint of said bubble vial, saidviewing plane being located on a viewing face of said body parallel tosaid level face, the ends of said bubble vial not extending beyond saidlevel face or said viewing face; and a transparent window located onsaid viewing face such that along said first line of sight the image ofsaid bubble vial transferred by said mirror can be viewed through saidwindow, and along a second line of sight which is not parallel to saidfirst line of sight and which passes through said window an interiorportion of said body can be viewed, wherein said mirror intersects saidwindow.